DOMS

But delayed onset muscle soreness isn't a bad thing.  In moderation, it indicates progress.

I'm rather tired today and there are a few factors, but I think they include DOMS:

1. DOMS (hilly run and zwow yesterday)
2.  Gluten exposure on Saturday. 
3.  Not enough sleep.  I took some ZMA before bed and fell into a deep sleep at about 11, but I got woken up repeatedly from 5-7 am due to courting birds and heavy artillery (the closest thing is a military training area, and spring is starting and this one hopeless lovelorn bird displayed his ignorance of Einstein's definition of insanity over and over and over again.  I think the pathos got to me more than the racket all of the other birds combined: I started imaging a scene in a small French village where a spurned young lover keeps trying, but the tanks are rolling in...).  Anyway, it seems that I need about 7 - 7.5 hours of sleep a night these days, and six just doesn't cut it.

It's kind of inconclusive to sift out DOMS from all that, but I took the dog for an hour-long hike and, at times, certain muscles protested more when they were required more.  This is somewhat uncomfortable, yes, but also much more satisfying than the constant soreness of gluten exposure.

During my healthier periods in the past, I had a regular cycle of sore/easy and not sore/tough days, usually 3 tough workouts a week.   This is what I'm hoping to get back to.   It doesn't matter that my hard days would've been easier in the past.  As long as they continue to feel hard, and I remain consistent with exercise and diet (mainly, avoiding gluten, that simplifies a lot), they will become more difficult.